Later today, the Senate will begin to debate immigration. There’s no actual bill on offer — Majority Leader McConnell will bring a shell bill to the floor, and then the amendments will begin. Whatever gets 60 votes will prevail. Perhaps for this week, at least, the “World’s Greatest Deliberative Body” won’t be a sarcastic joke.

One of the first and most important topics for debate should be the breadth of the proposed amnesty. Who should qualify? DACA only or DACA-plus? The range goes from the roughly 700,000 who now have DACA work permits (as in Bob Goodlatte’s bill in the House), to the 1.8 million suggested by the White House, to 3 million or more under other proposals.

I criticized the White House proposal when it was announced, arguing, among other things, that we should start by amnestying only the DACAs. Jason Lee Steorts here at NRO and Conor Friedersdorf at The Atlantic took issue with my piece and approved President Trump’s goal of expanding the amnesty to encompass more than 1 million additional illegals who either chose not to apply when they could have or were too young to have done so.

There are two separate issues in considering the scope of a DACA-plus amnesty: the “DACA” and the “plus.” The rationale for each is different.

The case for amnestying the people with DACA work permits (or rather upgrading them from Obama’s sketchy amnesty-lite to a lawfully enacted amnesty-premium) can be purely pragmatic. The issue is not, as Friedersdorf writes, that “a decision to trust and enroll in what conservatives regard as a straightforwardly unlawful big-government program is the most important factor in whether one should be an American.” Rather, President Trump inherited a mess from his predecessor and, while Obama’s actions were unlawful, they have created facts on the ground that, as conservatives, we arguably should acknowledge.

DACA’s illegality is on Obama, not the 800,000 people who applied in good faith, paid fees, were issued work permits, and were lawfully hired. (This is larger than the widely reported 690,000 number because some of the original DACAs were deported for crimes, others failed to renew the two-year permits, and yet others married Americans and thus got green cards.) Despite Judge William Alsup’s risible ruling (likely to be overturned soon by the Supreme Court), DACAs have no legal right to that status. I nonetheless think it prudent to legalize them, so long as we can limit the fallout from the amnesty by tightening enforcement, limiting future chain migration, and offsetting the increase in green cards with cuts in legal immigration.

Amnesty for the DACAs is not especially controversial; even the Goodlatte bill in the House, which has been endorsed by Numbers USA, the nation’s leading restrictionist advocacy group, would legalize the current DACAs.

It’s the “plus” part of DACA-plus that warrants a closer look.

In supporting the White House’s broader amnesty, Steorts notes the usual arguments: Even the non-DACA dreamers are “deeply rooted here, often with no plausible alternative,” and they “are not blameworthy for having entered the country without authorization.” Friedersdorf makes the same points about DACAs “who were brought here as children through no fault of their own”: We should not “needlessly consign them to an unfamiliar country.”

In other words, Steorts and Friedersdorf are arguing for the DREAM Act, first introduced in 2001, and rejected at least twice by the Senate. (DACA, Deferred Action for Childhood Arrivals, is the administrative version of the Dream Act, decreed unlawfully by Obama to increase Hispanic registration and turnout for the 2012 election.) But why are the eligibility requirements of DACA and the DREAM Act the correct ones — most significantly, arrival before age 16 and five years’ residence? (There were also very loose education and criminal-record requirements.) It’s only a slight simplification to say that upgrading the DACAs is a matter of changing one of the cells in an Excel file — they’re already in the system. But to expand beyond DACA would be to establish a whole new amnesty program, from scratch, and requires a delineation and justification of its eligibility requirements.

In seeking a rationale for these requirements, we should look to the two main arguments for DACA/Dream, as noted above: “no fault of their own,” and “they know no other country.” The former is little more than a talking point — after all, children often suffer for their parents’ mistakes. When the bank forecloses on a house because the adults can’t pay the mortgage, the children don’t get to stay because the loan default was “no fault of their own.”

It’s the second rationale that forms the core of the argument for DACA/Dream, both in principle and in winning public support. Because of our political class’s mulish refusal to enforce immigration laws, there really are young-adult illegal aliens who don’t know any other country, who’ve had all their schooling here, whose identities were formed here as Americans.

But, contrary to the Dream Act, none of them came as teenagers. And it didn’t happen in five years.

Is it really plausible that someone who came here at 15½ would become ‘an American in all but paperwork’ by his 21st birthday?

I have never heard a good explanation for setting an arrival age so late and a period of residence so short. Is it really plausible that someone who came here at 15½ would become “an American in all but paperwork” by his 21st birthday?

No one actually believes that, and yet all the proposals for expanding the amnesty beyond DACA use these same criteria. (Almost all — the Durbin/Graham Dream Act of 2017 actually raises the age at initial arrival to 18 and shortens the period of residence to four years, expanding the estimated number of potential beneficiaries to 3.6 million.)

In identifying adults who came here so young, and have been here so long, that they are psychologically and emotionally Americans, a more plausible age-at-arrival cutoff is seven years old and a ten-year period of continual residence in the United States. Psychologists find that ages six to seven mark an important milestone in children’s cognitive development (including their national identification), which is why the “age of reason” in both the common law and canon law is seven. This is also when schooling begins in many countries (and when it moves beyond babysitting here). An adult who has lived here since age seven truly has been socialized as an American.

You may disagree. Maybe you think the age at first arrival should be three, so there are no memories of the old country at all. Alternatively, age twelve for most people is the cutoff for being able to learn to speak a second language without an accent. Also, you may think ten years of continuous residence is too long, or too short.

But whatever your preference, you are obliged to make a case for it. Any gangs of senators (or an administration) arguing for an amnesty that goes beyond simply cleaning up Obama’s DACA mess needs to offer reasons for where the lines are drawn. The fact that Dick Durbin decided to require initial arrival in the U.S. by age 16 when he wrote the original Dream Act in 2001 is hardly a persuasive justification.